v0.2.0 — the adapter release

Every protocol adapter is now live-validated against its real vendor — plus a barge-in
policy engine, caller-context + welcome-greeting, and box-level mTLS.

Adapters

• New: vapi (WebSocket transport), assemblyai + cartesia (streaming STT → new
  earshot::transcript event).
• Fixed to work against current APIs: elevenlabs (required convai subprotocol +
  respects codec/rate), gemini (JSON-over-binary frames + realtimeInput.audio +
  current model).
• All ten adapters validated: native · twilio · openai · deepgram · elevenlabs · gemini ·
  pipecat · vapi · assemblyai · cartesia.

Features

• Barge-in policy engine — interruptible=none|dtmf|speech|any, sensitivity,
  ignore_backchannel, barge_min_ms, barge_fade_ms.
• Caller context + welcome greeting — EARSHOT_META → X-Earshot-Meta header;
  greeting= / EARSHOT_GREETING.
• Box-level mTLS + custom CA — EARSHOT_TLS_CLIENT_CERT / _KEY / EARSHOT_TLS_CA.
• New event earshot::transcript (STT).

Full details in CHANGELOG.md.

Full changelog: v0.1.0...v0.2.0